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Expanded Cyclotetrabenzoins.

Andrew M Eisterhold¹, Thamon Puangsamlee¹, Steffen Otterbach²

¹Department of Chemistry, University of Houston, 3585 Cullen Boulevard #112, Houston, Texas 77204-5003, United States.

Organic Letters

|January 7, 2021

Summary

This summary is machine-generated.

New cyclotetrabenzoin macrocycles were synthesized using N-heterocyclic carbene catalysis, showing distinct regioselectivity compared to cyanide methods. These shape-persistent molecules offer potential for advanced materials.

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Area of Science:

Organic Chemistry
Materials Science
Supramolecular Chemistry

Background:

Cyclobenzoins are shape-persistent macrocycles crucial for developing optoelectronic and porous materials.
Previous syntheses often relied on cyanide catalysis for cyclotetrabenzoin preparation.

Purpose of the Study:

To synthesize novel cyclotetrabenzoin macrocycles utilizing N-heterocyclic carbene (NHC) catalysis.
To investigate the regioselectivity of NHC-catalyzed synthesis compared to traditional cyanide-catalyzed methods.
To explore post-synthetic modification of the synthesized macrocycles.

Main Methods:

N-heterocyclic carbene (NHC)-catalyzed benzoin condensation was employed for synthesis.
Biphenyl, naphthalene, and tolane skeletons were used as precursors.
Crystal structures of cyclotetrabenzoin acetic esters were determined.
Post-synthetic functionalization of tolane-based cyclotetrabenzoin with Co2(CO)6 moieties was performed.

Main Results:

New cyclotetrabenzoin derivatives were successfully synthesized from biphenyl, naphthalene, and tolane precursors.
The NHC-catalyzed synthesis exhibited different regioselectivity compared to cyanide-catalyzed routes.
Crystal structures confirmed the molecular architecture of two novel cyclotetrabenzoin acetic esters.
Alkyne groups on the tolane-based macrocycle were effectively functionalized.

Conclusions:

NHC catalysis provides a viable and regioselective alternative for synthesizing cyclotetrabenzoin macrocycles.
The synthesized macrocycles, particularly the tolane derivative, are amenable to post-synthetic modification for advanced applications.
These findings expand the synthetic toolbox for creating complex macrocyclic architectures for materials science.